This invention relates to four-wheel drive motor vehicles and, particularly, to four-wheel drive motor vehicles employing a drive transfer gear assembly in the drive train which functions to apportion the torque between the front and rear drive axles.
Many drive transfer gear assemblies of the torque proportioning type have been proposed heretofore. However, these prior art units have met with, at best, only limited commercial success because of several disadvantages. Specifically, these prior art units, particularly when equipped with a one-way clutch device to lock up the gear set upon front wheel overspin, fail to anticipate and make satisfactory provision for particularly damaging torque overload conditions that applicant has found to be generated in various special situations. Further, the one-way clutches provided with these prior art units have been of a relatively bulky and relatively expensive design and the durability of these clutches has been found to be marginal in certain duty cycles. Further, these prior art devices, by their inherent design configuration, have created a relatively high center of gravity for the total rear axle assembly and have complicated the job of providing clearance between the front axle drive shaft and various drive train components.